Improvement in dredging-machines



'R. G. PACKARD. Improvement in Dredging-Machine's. No. 131,825.

Patented Oct.1, 1872.

UNITED STATES PATENT OFFICE.

RALPH G. PACKARD, OF BROOKLYN, NEW YORK.

IMPROVEMENT IN DREDGlNG-MACHINES.

Specification forming part of Letters Patent No. 131,825, dated October1, 1872.

powerful purchase to take hold of the mud or earth and inclose it andlift it between the scoops. This style of dredger is very extensivelyused and is familiar to all engaged in the business. My improvementconsists in important modifications of the construction and arrangementof the scoops and operating mechanism attached to or adjacent to thesame; it allows a stronger and lighter construction of the scoopsthemselves it provides for a more elevated position of the shaft and itsconnections by which the scoops are opened and closed; providesadditional safeguards against the liability of the opening and closingchains to become displaced or foul; makes the parts stiffer, stronger,and more manageable with less weight and complication.

The followingis a description of whatI consider the best means ofcarrying out the invention. The accompanyingdrawingforms a part of thisspecification.

Figure 1 is an end elevation of the scoops and the adjacent parts withFig. 2 is afront elevation with the scoops closed. Figs. 3 to 6,inclusive, represent details,.detached, shown on a larger scale. Fig. 3represents the opening and closing shaft with its pulleys, chain-guard,&c., and one side of the sliding frame-work which supports the bearingsof the shaft and travels up and down in the main framing. Fig. 4 is anend elevation of the same shaft and pulleys with the chainguard inposition. Fig. 5tis atop view of the cross-piece or bridge-tree, whichforms the top of the main frame, and which receives and rigidlyconnects'to a vertical pole to aid in supporting the mechanism in avertical position, when it is allowed to descend rapidly.

Fig. 6 is aside view of the .same part. Figs.

the scoops open.

7 and 8 represent modifications in some of the details. Fig. 7 is an endelevation, partly in section. This modification is intended to apply toboth open-ended and close-ended scoops.

Fig. 8 is a face view.

Similar letters of reference indicate corresponding parts in all thefigures.

A A are the uprights of the main frames. A is the upper cross-piece orbridge-tree, and A the lower rigid connection. These constitute arectangular rigid framing, and the presence of the lower connection Agives it a stiffness which is not found in the corresponding parts ofthe ordinary framing for this species. of

Work. In the ordinary frames the operatingshaft is so near the lower endof the frame that there is not the proper room for any rigid connectioncorresponding to the cross-piece A Within suitable spaces provided inthe upright partsA of the main frame runs a sliding frame, B B, (seeFig. 3,) composed of two uprights, B, and across-piece, B, and carryingin suitable bearings the operating-shaft O. This shaft performs theimportant functions of opening and closing the scoops. The chains bywhich this-operation, as also the raising and lowering of the entirestructure, is performed, are received upon pulleys G and O the pulley 0being much larger than the pul-.

leys 0 There are other pulleys, 0 upon which other chains are received.The closing chain D winding upon the large pulley O closes the scoopsand raises the entire structure. It acts with great leverage, and, inthe act of lifting the loaded scoops, pinches them together with greatforce. This is closely analogous to the operation of the correspondingparts in the ordinary dredger; but the arrangement of this part and theconnections by which the operations are effected have important pointsof difference. The shaft 0 and its connections rise and sink within themain frame at each operation. The scoops M M turn on a single pivot oraxis, m, which, being above the center of their cylindrical form, givesthe scoops an eccentric motion, so

as to open clear of the cross-bar and also clear of the chains. It alsocauses them to cut themselves clear in moving through the mud, bysomoving that the backs or general curved surface does not forcibly pressagainst the earth which is left. Their front edges alone press tightlyagainst the mud or sand. The arrangement allows them to hang on a singleaxis, and they are strongly connected by the straps represented. Theoperating rods or links 0 0 lead from proper points or pins N N on theends of the scoops M M and connect to pins P on the sliding frames B, asrepresented; or, if preferred, can connect directly to the shaft C. Whenthe shaft 0 with the sliding frame B is elevated it opens the scoops.This movement is effected by receiving the weight on the opening-chain DIn this condition the structure is lowered until the scoops rest on thebottom. Then, by slackening the openingchain D and causing thesteam-engine or other operating force (not represented) to take up theclosing-chain D, the haul on the closingchain turns the shaft 0 forciblyin the direction indicated by the arrow. This movement takes up thechains E, which are wound on the sheaves G and which are fast to thefixed cross-bar A and this movement hauls down the shaft G and itsconnections and thus the scoops are closed. This compound movement forclosing the scoops, being peculiar, may merit a further explanation. Thepull of the closin g-chain D itself tends, so far as its direct force isconcerned, to lift the shaft 0 and its connections. But the leveragebeing on the large pulley 0, this direct effect is slight, compared tothe ultimate eifect by winding the chains E on the pulley G which is theresult of the turning motion of the shaft 0. In other words, theclosing-chain D pulling upward with a force of one ton, acting at theperiphery of the large pulley 0, turns the shaft 0 with such force as totake up the chains E on the small pulley O with a force of three or fourtons, and the preponderance of this latter over the former force causesthe operatingshaft 0 and its connections, including the links 0, to beforcibly depressed and close the scoops. On the opening motion of thescoops the pull of the opening-chain D acts directly to both turn andraise the shaft 0 and its connections, and the chains E being entirelyrelaxed by the turning of the shaft 0 in theproper direction, there isno force resisting the rise of the shaft O and entire connectedmechanism B, 0,0, 850. The peculiar structure of the scoops with adouble skin is clearly shown in the drawing. The inner and outer skins zi may be of boiler-iron, secured by rivetin g upon the stout straps I,which connect together at each end and are strongly connected by rivetsthrough them and the ears. The outer ribs J may be also riveted, and, byprojecting past each other at the meeting edges of the scoops, performthe usual function of strongly clinging to any rock or other solidobject which may be encountered. They extend from the top of scoopdownward, and serve to give additional strength and stiffness to them.These points or teeth are analogous to the corresponding parts of theordinary dredgers, but the extension of their roots along the wholeextent of the curve. surface greatly increases their strength. Thedrawing shows how they are reconcilable with the double-skin construction of the scoops. The operating-chains D D are led up through holes Kin the upper cross-bar or bridge-tree A These holes are prolonged in thedirection of the length of the bridge-tree so as to allow the chains totraverse freely within reasonable limits in winding upon the sheaves,but they are of such limited length that the chains can move but alittle way longitudinally of the bridge-tree A and the fact of the chainbeing strongly guided in these holes tends to maintain the structure inan upright position by the tension of the chains, so that it may beoperated with success without the necessity for any guiding-pole. Itwill be understood that the central hole a in the bridge-tree A isadapted to receive a pole, which may be of any length, and serves tosteady and stiffen the structure, and also to hold the scoop down whenexcavating hard material. The side holes a a are introduced mainly tolighten the bridge-tree, but they may be made to receive guide-poles, ifit shall be necessary in any case to employ two. The opening-chain D isbranched near its lower end, forming two equal opening-chains. Theseparts are wound upon two similar small pulleys, 0 0 mounted one on eachside of the large closing-pulley O. This arrangement insures auniformity in the tension and avoids any tendency to tilt or incline thestructure either way when in operation. In other words, the pull on theclosing-chain D is directly central, and does not incline or tilt thestructure, and the pull on the opening-chain D is also directly central,and equally avoids any tendency to tilt or incline the structure.

It is important to the rapid opening of the scoops that theclosing-chain D shall be liberated and run out very freely. In order toavoid entanglement and prevent the chain D from dropping out of thegroove of the large wheel 0 and thus lose its leverage in closing thescoop it is important that its further running out shall be arrested atexactly the right point, so that all that is let out shall be woundsnugly upon the pulley or sheave G I accomplish this by attaching aweight, G, to the closing-chain D, taking care to fix it at exactly theright point, so that it shall be arrested by striking on the cross-bar Bof the sliding-frame B at the moment when a sufficient amount of theclosing-chain has been hauled down and wound upon the sheave 0 Thispiece of metal Gr should be of considerable weight, so as to assist inhauling down the chain D. It thus performs the double function of aweight to overhaul the chain D and of a stop to prevent its beingoverhauled too far. When the closin g-chain is hauled up this weightruns freely through the fair-leader K, which must be of sufficient sizeto allow its passage. So soon as the closing-chain is slackened, themass G assists by its weight to haul down the chain, and thus assists inthe opening of the scoops. But so soon as a sufficient mischief. Evenwith this precaution against the accumulation of slack closing chainthere is still a possibility that the closing-chain may get off of thelarge pulley O and commence to wind upon the shaft 0 or upon one of thesmall sheaves 0 instead of maintaining its proper place on the largesheave G I guard against this by means of the chain-guard H, which is inthe form of a wide strap, encircling all the lower portion of the sheaveO, with lips folded inward against the faces of the sheave to preventthe guard from getting displaced. The chain-guard H is fastened by eachof its ends to the cross-piece B and is divided and braced at and nearthe. points of attachment, as shown in Fig. 3. ,It affords ample spacein the deep groove within the sheave G for a complete turn of theclosing-chain. It may hold two or more turns,

if necessary. The groove in the sheave 0 should be made deep, for thedouble purpose ,of storing freely a sufficient quantity of chain and ofdiminishing the chance of the chain getting out of the groove. Withregard to the opening-chainthe intention is to make the pulley G of suchdiameter as tO'OVGIllEtIll the closing-chain D and turn the shaft 0against the friction of its journals. There are cases when the Windingof the chain D on the pulley may be objectionable, because, in openingthe bucket, it is lowered by their unwinding. In those cases the pulleys(3 should be omitted and the chains should be attached directly to theshaft or to rings which encircle the shaft, so as not to wind upon it.

Referring to the modifications shown in Figs. 7 and 8, it will beobserved that the end elevation, Fig. 7, shows the ends of the scoopsentirely open and the two skins of the curved sides fixed further apartand inclosing between them thicker and. heavier framing than in theordinary form. This is poorly adapted to dredge up mud, but servesadmirably, by its immense strength, to take up rocks and other heavymasses. In this form there are, as before, both longitudinalstrengtheningpieces and pieces extending up and down the scoops, and theupand-down pieces are extended, as before, to form teeth, which matchpast each other as the scoops close; but in this form the longitudinalpieces do not, of themselves, fill the whole space between the skins,but only by the aid of filling-pieces or stout blocks T, and theup-and-down pieces are between the skins, instead of outside. I havemarked these parts u ith the same letters of reference as before, andconsider them equivalents in their relations to each other and to theskins, although arranged with special referenceto dredge hard solidsinstead of soft mud or sand.

Fig. 8 gives another view of the scoops,

substantially shown in Fig. 7, but slightly modified.

Among the marked advantages due to my arrangement for causing theoperating-shaft (J to rise and sink, as shown, are the following: Myarrangement allows the scoops to open wide, even so as to touch eachother -with their backs, which is not possible when the shaft is mountedin fixed bearings. Again, the shaft-bearings are high up and out of themud and grit when the scoops are lowered.

Again, the elevation of the shaft saves it from breakage in case thestructure strikes on a rock in being lowered rapidly. Furthermore, itallows a larger closing-wheel, so as to give any amount of purchasedesired from this source. Also, it avoids the risk of the cutting of thebacks of the scoops by the contact of the closingchain therewith and,finally, it causes a partial balancing of the strain, very important inpractice, on the several pulleys. In my arrangement the chain from thelarge opening-sheave U pulls in one direction, and the strains on thetwo smaller pulleys O G are in the opposite direction, while those withthe shaft in fixed bearings have the strains on all in the samedirection.

, I claim as my invention- 1. The rising-and-sinking shaft 0, carryingthe pulleys and connections for opening and closing the scoops, andconnected to the scoops M by the links 0, or their equivalents, as andfor the purposes specified.

2. The scoops M M constructed with the double skiniiand with stiffeningand stren gthening parts I J, forming the cellular construction, asspecified.

3. The heavy stop G fixed in the right position on the closing-chain Dand adapted to serve relatively thereto, to perform the double functionsof a weight and stop, as herein specified.

In testimony whereof I have hereunto set my name in presence of twosubscribing witnesses.

' RALPH G. PACKARD.

Witnesses:

O. C. LIVINGS, A. HOERMANN.

